1. Field of the Invention
The present invention relates generally to flat video displays and, more particularly, to the control of Liquid Crystal Displays (LCDs) to achieve power savings.
2. Description of the Related Art
Liquid crystal displays (LCDs) are rapidly displacing traditional cathode-ray tube monitors in popularity because the LCDs take up less space, consume less power, and offer crisp text compared to the cathode-ray tube monitors. LCDs work on principle of twisting/polarizing liquid crystal material under the influence of an electric field. With some LCDs, light passes from a backlight source through a first polarizer, passes through a layer of liquid crystals, passes through a colored filter, and then passes through a second polarizer that is oriented 90 degrees from the first polarizer. When light cannot pass through the second polarizer, the pixel appears black. An electric field created around the liquid crystal material twists the LCD material, which bends the light and lines the light up with the second polarizer allowing the light to pass through when the pixel is turned on.
LCD displays are often driven using Thin Film Transistors (TFTs). With displays of this type, TFTs are arranged on a glass substrate immediately below a layer of liquid crystal material pixel elements with each TFT altering the state of liquid crystal material of a corresponding pixel. Driving TFTs to a switched on state causes the corresponding pixel to turn-on. The liquid crystal material of an LCD pixel will usually untwist naturally when a corresponding TFT is not driven. The TFTs can be driven to an off-state and, driving the TFTs rapidly from an off state to an on state is usually required when displaying fast moving images such as video. Rapid switching of the TFTs that is required to display video results in more drive power consumption of the TFTs of the LCD.
When an LCD monitor is used for viewing and editing text, for example, a less expensive, slower, and lower power consuming LCD monitor may be used. A viewer who watches action films and plays graphically intensive video games from time to time may justify the higher cost and power requirements associated with a high speed LCD monitor even though much use of the LCD is for slow moving images, e.g., text editing, web page browsing, etc. With many LCD monitors, LCD pixels are typically driven for maximum speed twisting and untwisting even though such performance is not generally required. Such operation consumes significant power, which is particularly problematic for hand-held devices that are battery powered.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of ordinary skill in the art through comparison of such systems with various aspects of the present invention.